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| author | Keith Randall <khr@golang.org> | 2016-03-06 16:58:30 -0800 |
|---|---|---|
| committer | Keith Randall <khr@golang.org> | 2016-03-21 19:10:24 +0000 |
| commit | 6a33f7765f79cf2f00f5ca55832d2cfab8beb289 (patch) | |
| tree | d1cd6a803e32d952e60290c4c863c65bd88db808 /src/runtime/memmove_386.s | |
| parent | b07a214d39814545bbcd1d30f1850a95752dac65 (diff) | |
| download | go-6a33f7765f79cf2f00f5ca55832d2cfab8beb289.tar.gz go-6a33f7765f79cf2f00f5ca55832d2cfab8beb289.zip | |
runtime: use MOVSB instead of MOVSQ for unaligned moves
MOVSB is quite a bit faster for unaligned moves.
Possibly we should use MOVSB all of the time, but Intel folks
say it might be a bit faster to use MOVSQ on some processors
(but not any I have access to at the moment).
benchmark old ns/op new ns/op delta
BenchmarkMemmove4096-8 93.9 93.2 -0.75%
BenchmarkMemmoveUnalignedDst4096-8 256 151 -41.02%
BenchmarkMemmoveUnalignedSrc4096-8 175 90.5 -48.29%
Fixes #14630
Change-Id: I568e6d6590eb3615e6a699fb474020596be665ff
Reviewed-on: https://go-review.googlesource.com/20293
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Diffstat (limited to 'src/runtime/memmove_386.s')
| -rw-r--r-- | src/runtime/memmove_386.s | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/src/runtime/memmove_386.s b/src/runtime/memmove_386.s index 9a21e84136..d4baf2280a 100644 --- a/src/runtime/memmove_386.s +++ b/src/runtime/memmove_386.s @@ -69,13 +69,25 @@ nosse2: /* * forward copy loop */ -forward: +forward: + // Check alignment + MOVL SI, AX + ORL DI, AX + TESTL $3, AX + JNE unaligned_fwd + MOVL BX, CX SHRL $2, CX ANDL $3, BX REP; MOVSL JMP tail + +unaligned_fwd: + MOVL BX, CX + REP; MOVSB + RET + /* * check overlap */ |